Setup of Compton polarimeters for measuring entangled annihilation photons

TL;DR

This paper presents an experimental setup using Compton polarimeters to measure and compare the polarization states of entangled and decoherent 511 keV annihilation photons, advancing quantum state analysis techniques.

Contribution

It introduces a novel experimental setup with dual Compton polarimeters and a GAGG scintillator for studying entangled and decoherent photon states in positron-electron annihilation.

Findings

Measured polarization modulation factors for entangled photons.

Compared Compton scattering in entangled and decoherent states.

Evaluated performance of different Compton scatterers and detectors.

Abstract

An experimental setup for studying the Compton scattering of annihilation photons in various (entangled and decoherent) quantum states is presented. Two entangled $\gamma$-quanta with an energy of 511 keV and mutually orthogonal polarizations are produced by positron-electron annihilation in a thin aluminum plate and are emitted in opposite directions. To measure both photons, the setup provides two equivalent arms of Compton polarimeters. A Compton polarimeter consists of a plastic scintillation scatterer and an array of NaI(Tl) detectors for measuring photons deflected at an angle of 90$^\circ$. The intermediate scatterer of the GAGG scintillator with SiPM readout is inserted into one of the arms to create a tagged decoherence process prior to the measurement of annihilation photons in polarimeters. The performance of Compton scatterers and NaI(Tl) counters is discussed. The polarization modulation factor and the analyzing power of Compton polarimeters are evaluated from the angular distributions of scattered gammas. The Compton scattering of photons in entangled and decoherent states is compared reliably for the first time.